Electron discharge device



June 7, 1938.; v 1 RONCI 2,119,559

ELECTRON DISCHARGE DEVICE Filed July 25, 1955 2 Sheets-Sheet 1 4a 57 as4 2 4 L I L 1 v I 74 w I lNVEN TOR l4 LRONC/ AT TORNEV June 7, 1938. v.L. RONCI 2,119,559

ELECTRON DISCHARGE DEVICE Filed July 25, 1935 2 sheets-sheet 2 //v lENTOR ML. RONC/ Br ATTORNEY Patented June 7, 1938 ELECTRON DISCHARGEDEVICE Victor L. Ronci, Brooklyn, N. Y., assignor to Bell TelephoneIaboratories,,-'Incorporated, New York, N. Y., a corporation of New YorkApplication July 25, 1935, Serial No. 32,985

22 Claims.

This invention relates to electron discharge devices of the Braun typein which an electron beam is projected toward a screen on the oppositeend of the device.

An object of the invention is to facilitate the alignment of theelectrodes in cathode ray dis charge devices and to secure a ruggedconstruction of the electrode mounts.

In accordance with the general aspect of this invention, the cathode raydischarge device comprises an electrode mount constructed as a unit andwhich is sealed into the end of a large vessel which contains thefluorescent screen. This assembly insures. accurate alignment of theelectrodes to facilitate the projection of the cathode ray beam alongthe axis of the vessel. Furthermore, the rugged construction of theelectrode mounts increases the static characteristics of the device.

A feature of the invention relates to the assembly of the electron gunon a platform mounted on a stem. This assembly comprises'an indirectlyheated cathode fixed to an insulating base or platform with acylindrical control or modulating electrode surrounding the cathode. Anelongated focussing anode is also mounted on the platform and isprovided with baifle members at opposite ends havingaligned aperturesfor concentrating the electrons into a narrow beam.

Another feature of the invention relates to the mounting of thedeflector plates in proper relation to the electron beam and to insureaccurate alignment of the plates. This assembly comprises a tubularshell or sleeve sealed to the neck of the glass portion of the electrodeunit, the shell forming a rugged support for an apertured .block whichcarries an internal tubular metallic element located between the shelland the end of the anode. A pair of posts extend from the block andcarry an apertured insulating platform having slots on both sides toreceive a pair of depending deflector plates and a pair of extendingdeflector plates, one pair of plates being at right angles to theotherpair of plates.

Another feature of the invention relates to the provision of resilientsprings or fingers on the deflector plate mounting platform to formfriction contacts for the conductivecoating on the interior wall of theenclosing vessel.

A further feature of the invention relates to the sealing arrangement ofthe conductors of the deflector plates. In the assembly of the completedevice these conductors are loosely arranged between a bulbous portionof the mount assembly and the neck of the enclosing vessel. Afteraccurate alignment of the mount within the vessel the conductors aresealed in the glass by a flow method in which the neck of the vessel isunited to the mount assembly and the conductors are spaced in anannuluar formation which forms a sealed joint between the vessel and themount.

These-and other features of the invention will be more clearlyunderstood from the following detailed description when read with theaccompanying drawings.

- Fig. 1 is a cross-sectional view in elevation of a cathode raydischarge device made in accord ance with this invention and showing therugged assembly of the electrode units in alignment to control theprojection of a cathode ray beam toward a fluorescent screen on the endof the device; W

Fig. 2 is an enlarged perspective view of the mount assembly of theelectrodes with portions of the glass member and electrodes broken awayline 44 of Fig. 1 and showing the arrangement oi the conductors'of thedeflector plate unit and the radial contacts on the external base;

Fig. 5 is an enlarged view in elevation of a modification of theinvention pertaining to the electron gun assembly in which theelectrodes are shown in cross-section to illustrate the detailconstruction;

Fig. 6 is a plan view of the assembly shown in Fig. 5 illustrating thesymmetrical mounting of the elements; and

Fig. 7 is a perspective view of a modified ring base for the deviceshown in Fig. 1 with a clamp for connecting it to the vessel.

Referring particularly to Figs. 1 and 2, the discharge device, in oneaspect of this invention, is embodied in an elongated enclosing vesselformed of a long tubular portion or neck I 0, and an outwardly'flaredconical portion I l which terminates in a dome portion l2. The longtubular portion I0 is joined to an extending tubular mount portion l3having an inwardly projecting stem M. a tubular end portion l5 reentrantwith respect to the tubular portion l0 and an annular nodal or bulbousportion it which is fused to the end of the tubular portion I 0. Thetubular portion It! has a section thereof and the conical portion coatedwith a continuous opaque conductive material l'l such as "Aquadag".commonly known as colloidal graphite. to prevent theaccumulationofelectricchargesontheglasswallofthe vessel and to serve asan accelerating electrode.

' This coating also prevents reflection losses and therefore tends 'toincrease the eiiiciency of the device in operation. A fluorescentcoating material ll is applied to the dome portion I2. to perscreen andit is obvious that in order'to concentrate the beam of electrons alongthe axis of the device it is essential to coordinate the variouselements which aid in concentrating the beam and in controlling themovement of-the beam so that the highest efllciency may be obtained witha minimum of loss, caused by divergence of the beam, misalignment of thecontrolling elements and variations in spacing of the controllingelements.

In accordance with this invention all the focussing and controllingelements cooperating to produce the concentrated beam of light along theaxis of the vessel are combined in a single unit or mount which may beruggedly constructed to insure constant and positive alignment of theelectrode elements to obtain the highest emciency' in the device. .Inorder to understand the detail construction of the electrode mount,attention is directed to Fig.1 which shows this assembly in enlargedform. The stem i4 projecting within the lower end of the tubular memberI! is formed into a press I! having three arms or wings radiating from acentral point and equally spaced from each other. A support rod 20extends vertically from the outer end of each arm of the press It andthe three rods form a tripod support for a circular disc or platform 2|,the platform being held in position on the rod by welding short stubwires to the rods 20 above and below the I platform 2|.

The platform 2| serves as a rigid base for mounting the elements of anelectron gun assembly for projecting a concentrated beam of electronsalong the axis of the device toward the fluorescent screen IS on thedome portion of the enclosing vessel. The electron gun consistsprincipally of a central cathode or emitter 28 and an elongated tubularfocussing anode 24. The detail assembly of the cathode is shown moreclearly in Fig. 5 and comprises an internal heater element 25 surroundedby an insulating sleeve 26 which is substantially enclosed by a metallicthimble 21, coated with electron emissive material, such as barium andstrontium oxides.

. The cathode assembly 23 is mounted in the axis erably of nickelsilver, having opposite ends undercut by increasing the inner diameterof the ariasso I restsagainsttheannularseatformedbythe cuttingoperation. The bailie discs or partitions areheldsecurelyagainsttheirseats by atubular metallic insert 33 which fits into the increaseddiameter of the ends of the tubing'and is held therein by spinning overthe outer wallofthe end sections of the tubing.

The interior wall of the tubular anode and the inner faces of the bailiepartitions are coated with an electron collector material 34, such ascolloidal graphite, to prevent the liberation of secondary electronsfrom the anode. The anode 24 is arranged in position so that the centralapertures in the baiile discs 32 are in alignment along the axis of thecathode 23 in orderto project the beam of electrons along this line. Theanode 24 is elevated from the platform 2|, to space the lower bafliedisc 32- in theanode in suitable relation to the end of the cathodethimble 21. In order to support the anode in thisposition threetangential braces 35 have their upper ends secured to the anodeintermediate the ends thereof and extend outwardly to the circumferenceof the platform 2| with the lower ends of the braces bent inwardly andsecured to flanged pins 36 which are staked in the platform 2| with eachpin equally spaced between the projecting ends of the tripod rods 20. Acylindrical metallic electrode I'l coaxially surrounds the cathode 23and is overlapped by the lower end of the anode 24. This electrode isseated in a circular recess of the platform 2| and is held in positionby staked pins extending through the platform. The cylindrical electrode31 may serve as a shield to prevent the escape of electrons from thecathode or 4 a suitable potential may be applied to the cylindricalelectrode 31 to serve as a control electrode or a modulating electrode.when the cylindrical electrode 31 serves as a controlling electrode asuitable connection is necessary to apply the desired potential thereto.As shown in Fig. 2,.a connecting wire 38 is secured to the cylindricalelectrode 8'! and welded at the other end to one of the tripod rods 2|.4 Since a high potential is applied to the focussing anode 24 a suitableleading-in conductor may be provided for this electrode by connectingone of the braces 35 to the remaining tripod rod 20, the tripod rodshaving suitable leading-in conductors extending through the hollowportion of the stem l4 and 1 connected to terminals 39 on a base 40which is secured to the lower end of the tubular extension IS. Theheater wires 29 and 30 are also provided with'leading-in conductorsthrough the stem and connected to other terminals on the base 40. Theassembly of the electron gun provides a rigid structure which preventsthe escape of electrons in a lateral direction to the glass wall of thetubular extension and insures the projection of the electron streamalong the axis of the focussing anode to produce a concentrated bundle"of cathode rays which is focussed to a high degree by the baiilepartitions in the elongated anode.

A modification of the electron gun assembly of this invention is alsoshown in Fig. 5 in which the anode 24 is formed of light metal tubingwhich is supported from the pins 3 by metallic elbows 4|. A pair ofhaflle partitions 42 are situated in opposite ends oi the anode and areformed of flanged metallic members welded or brazed to the inner surfaceof the anode and provided with aligned central apertures for focussingthe electron beam. A cylindrical control electrode or shield 43surrounds the cathode and is provided with a closure cap 44 having acentral aperture in alignment with the apertures in the partitions 42and the end of the cathode 23. In this arrangement the platform 2| isseated on the tripod rods 20 and an L-shaped wire passing through theplatform is secured to each tripod rod and a short stub wire 22 isfastened to the L-shaped wire above the platform. The control electrode43 is provided with a connector 46, as shown in Fig. 6, which is weldedto one of the L-shaped wires 45 and a similar connector 41 joins theanode to another L-shaped wire 45,

In addition to the projection of a concentrated beam of electrons to thefluorescent screen to produce a sharply defined spot of light thereon,

it is essential to provide a group of deflector plates in order tocontrol the sweep of the electron stream over the whole surface of thefluorescent screen. A feature of this invention is to mount thedeflector plate unit in coaxial alignment with the electron gun assemblyand to decrease the dimensional area of the mount for the deflectorplate unit sothat the unit will fit into the tubular portion ill of thevessel so that the highest efficiency may be attained with theconductive coating I I on the wall of the vessel. more, it is preferableto mount the deflector plate unit on the end of the member in which theelec-.

tron gun assembly is supported in order to obtain the highest degree ofefliciency between the two units.

In accordance withthis invention the tubular section l5 of the tubularextension which is reentrant with respect to the tubular portion III ofthe enclosing vessel is fused to a knife-edge portion of a coppersleeve, shell or collar 48 to form a rigid joint for the support of theunit. A metailic ring 49 having an oval-shaped flange 50 is supported onthe collar-48 with the ring being surrounded by the collar and theflange seated on the edge of the collar, the ring being secured to thecollar by screws 5|. The collar 48 is provided with longitudinal slots52 to compensate for slight variations in the diameters of the collar 48and the ring 49, thereby preventing mechanical strain on the sealbetween the metallic collar and the glass tubular portion. l5. Theflange 50 supthe ring 49 and closely surrounds the end of the focussinganode 24. This arrangement prevents the escape of any electrons from thebeam projected through the electron gun until it reaches the deflectorplate unit where it is controlled in accordance withwell-knownmi'actice. Furthermore, the special arrangement of the secondanode and the focussing anode insures an accurate alignment of thedeflector plate unit and the electron gun assembly due to theoverlapping of the anode 51 with respect to the end of the anode .24.

The insulating platform 54 is provided with parallel slots or guideways58 formed on the lower surface thereof and extending across one diameterof the platform and a second pair of guideways or slots 59 are formed onthe upper surface of the platform and these slots extend Furtheracross adiameter thereof at right angles to the and 6| are arranged in the slotsof the platform 54 and a similar pair of plates 62 and 63 are arrangedin the slots 59 of the platform to form a bounded passageway, as shownin Fig. 3, for the projection of the electron beam which is to becontrolled by the deflector plates in its passage between the plates.Each of the plates is provided with two extending wires 64 which projectthrough the platform 54 adjacent its respective slot, the wires beingbent. around the opposite surface of the platform to rigidly support theplates in position. This arrangement insures accurate parallelismbetween adjacent pairs of plates and true alignment of the two pairs ofplates since all the plates are mounted from a single member, namely theinsulating platform 54.

A ring type base 65, of insulating material, surrounds the end of thetubular portion III of the vessel and encloses the sealed junction ofthe portion II). This base is provided with a plurality of radialterminals 66 for applying suitable potentials to the deflector plates,individually,the accelerating anode 51, and the conductive coating II onthe interior of the vessel wall. The deflector plates'are connected tothe terminals 66 by rigid conductors extending from the plates andsealed through the, junction of the bulbous portion 5 and the 'end ofthe tubular portion III of the vessel in alignment with the terminals 66on the annular base 65. The top front plate 62, as shown in Fig. 2, isprovided with a long wire conductor 61 which is attached to the bentend'of the stub wire 64 of the plate and extends downwardly to thebulbous portion l6 of the tubular extension where it is sealed in thejunction of the bulbous portion and the tubular portion I 0 in alignmentwith one of the terminals 66, as shown in Fig. 4. The top rear plate 63has aconductor 68 similarly connected to the bent securing wire thereofand extending in alignment to the terminal 66 on the base. The lowerleft-hand plate is provided with a bent connecting wire in the forwardlower end thereof which is joined to a longitudinal conductor I0arranged in alignment with another terminal 66 on the base 65. Theright-hand plate 6| is provided with a bent connector H in the bulbousportion l6 and the end of the tubular The accelerating anode or secondanode 5 1 which is mechanically and electrically connected to themetallic ring 49 and flange. 50 is provided with a terminal conductor bysecuring a-strap I3 between the nut and the'flange 50 adjacent one ofthe supporting posts 53 and this strap is connected to a conductor 14.The conductor 14 is sealed in the junction between the bulbous portion[6 and the end of the tubular portion l0, as shown in Fig. 1, andconnected to its aligned terminal 66 on the base 65. The acceleratinganode 51 is usually operated at a high voltage, of about 2500 volts, toaccelerate the electrons projected through the focussing anode 24. Inorder to continue the influence of the high voltage of the acceleratinganode on the electron beam along the whole length of the vessel to thescreen, this potential is also applied to the graphite coating I"! onthe interior wall of the conical portion II and. the tubular portion H]of the platform 54. These fingers or contacts extend downwardly, asshown in Fig. 2, and are bent outwardly to form a friction contact sothat when the electrode mount is inserted in the enclosing -is shown inFig. 7 and provides an arrangement which permits the attachment of thebase to the vessel without the use of cement. Furthermore, the lateralarrangement of the terminal pins on the base facilitates the support ofthe device in a ring type socket mounted on a platform. In thisarrangement an annular insulating ring vl6 is provided with a splitcollar II which is clamped to the tubular portion ll! of the vesseladjacent the seal by a screw 18 and nut 19. A plurality of terminal pins80 are spaced around the lower surface of the insulating ring "I6 andextend parallel to the axis of the collar and ring. The

base may be applied to the device so that the terminal pins 80 arealigned with the respective leading-in conductors sealed through thejuncture of the bulbous portion I6 and the neck l0.

While the invention has been disclosed as embodying all the elementsdescribed, it is, of course, understood that the scope of the inventionis not limited to the particular combination since it is apparent thatdischarge devices may be constructed in which some of the elements areomitted. Furthermore, the invention is not intended to be limited to thespecific assembly described since various embodiments may be evolvedfrom the present disclosure and, therefore, the invention is only to belimited within the scope of the appended claims.

What is claimed is:

1. In combination, a mount for an electron discharge device comprising atubular'member having a larger diameter portion atan intermediate pointthereof and an inwardly projecting stem atone end, an electron gunsupported on said stem, a group of deflector plates supported on theopposite end of said tubular member coincident with-the axis of saidelectron gun, a plurality of conductors connected to said deflectorplates and extending outwardly toward said larger diameter portion, andan elongated vessel having a neck portion fused to said larger diameterportion and forming a sealed joint around said conductors.

2. In combination, a mount comprising a tubular member having aninwardly projecting stem, said tubular member having an annular nodalportion intermediate the ends thereof, an electron gun supported on saidstem, 9. group of deflector plates supported on said tubular membercoincident withthe axis of said ectron gun, an elongated vessel having aneck rtion of substantially the same diameter assaid nodal portion andsealed thereto, and a plurality of conductors leading to said deflectorplates, said con.- ductors having parallel straight portions arranged ina circular boundary intermediate said neck portion and said tubularmember and projecting outwardly from said vessel through the sealedjoint between said neck and nodal portions.

3. An electric discharge device comprising a vessel having a fluorescentscreen at one end and a neck portion at the other end, a tub 1r membersecured to said neck portion and naving a reentrant stem at one endthereof, an electron gun assembly projecting from said stem toward oneend and a neck portion at the other end, a

tubular extending portion forming a mount sealed to said neck portion,said tubular portion having a stem, a platform mounted on said stem,

a cathode and an elongated tubular anode coaxial therewith supportedfrom said platform, a plurality of deflector plates supported beyond theend of said tubular extending portion, and a plurality of conductorsextending from said plates, said conductors being sealed in the junctionbetween said neck and said tubular portions.

5. An electric discharge device comprising an enclosing vessel having afluorescent screen at one end and a neck portion at the other end, atubular extending portion forming a mount sealed to said neck portion,said tubulanportion having a stem at one 'end, a metallic collarextending from the other end of said tubular portion, an apertured blocksecured to said collar, an apertured insulating platform rigidly mountedon said block, a pair of spaced deflector plates suspended from saidplatform, a second pair of spaced deflector plates extending from saidplatform in opposed relation to the first pair, a cath-' ode and atubular anode supported from said stem, and a suspended metallic memberextending from said block and interposed between said collar and saidanode.'

6. An electric discharge device comprising a vessel having a fluorescentscreen at one end and a neck portion at the other end, a tubular memberhaving a bulbous portion of substantially the same diameter as saidneck. portion and sealed thereto, a portion of the tubular member beingcoaxially positioned within said neck portion, an annular ring securedto said tubular member withinsaid neck portion, a tubular metallicelement suspended from said ring, and an electron gun assembly includingan elongated anode supported in said tubular member, said anode having aportion extending into said tubular element.

'7. In an electron discharge device, an electron gun assembly comprisinga stem, a platform supported by said stem, a cathode supported by saidplatform along the axis thereof, a cylindrical electrode surroundingsaid cathode and mounted on said platform, and an elongated tubularanode projecting beyond said cylindrical electrode and having a portionoverlapping the ends of said electrode and said cathode.

8. In an electron dischargedevice, an electron gun assembly comprising astem, a platform supported on said stem, a cathode supported by saidplatform along the axis thereof, a cylindrical electrode surroundingsaid cathode and mounted on said platform, an elongated tubular anodeprojecting beyond said cylindrical electrode and having a portionoverlapping the ends of said electrode and said cathode, and a pluralityof supports connecting said anode to said platform.

9. In an electron discharge device, an electron gun assembly comprisinga stem, a platform supported on said stem, a cathode supported by saidplatform along the axis thereof, a cylindrical electrode surroundingsaid cathode and mounted on said platform, an elongated tubular anodeprojecting beyond said cylindrical electrode and having a portionoverlapping the ends of said electrode and said cathode, and a pluralityof equally spaced tangentially arranged braces projecting from saidplatform and connected to said anode intermediate the ends thereof.

10. In an electron discharge device, an electron gun assembly comprisinga stem, a platform supported on said stem, a cathode supported by saidplatform along the axis thereof, a cylindrical electrode surroundingsaid cathode and mounted on said platform, an elongated tubular anodeprojecting beyond said cylindrical electrode and having a portionoverlapping the ends of said electrode and said cathode, and a pair ofapertured baille partitions adjacent opposite ends of said anode.

11. In an electron discharge device, an electron gun assembly comprisinga stem, a platform supported on said stem, a cathode projecting from thecenter of said platform, a cylindrical electrode surrounding saidcathode and mounted on said platform, an elongated anode projectingbeyond said cylindrical electrode, said anode having inner undercutportions at opposite ends to form ring seats therein, a baflie platehaving a central aperture engaging each ring seat, and a retaining ringwithin each of said undercut portions abutting against each of saidbaflie plates.

12. In an electron discharge device, an electron. gun asembly comprisinga stem, a platform supported on said stem, a cathode extending from thecenter of said platform, an elongated tubular anode projecting beyondsaid cathode, baflle partitions adjacent opposite ends of said anode,and a nonrefiecting coating on the surfaces of said anode and saidbaflle partitions enclosed thereby.

13. In an electron discharge device, an electron gun assembly comprisinga stem, a platform supported on said stem, a cathode extending from thecenter of said platform, an elongated tubular anode projecting beyondsaid cathode, apertured baflle partitions adjacent opposite ends of saidanode, and a colloidal graphite coating on the inner surfaces of saidanode and said baffle partitions.

14. A mount for an electron discharge device comprising a tubular memberhaving a cylindrical sleeve at one end, an apertured platform spacedfrom said sleeve, and pairs of deflector plates supported by saidplatform, one pair of plates projecting above said platform and theother pair of plates extending below said platform.

15. A mount for an electron discharge device comprising a tubular memberhaving a cylindrical sleeve at one end, an apertured platform spacedfrom said sleeve, said platform having a pair of parallel slotsextending across one diameter on one side thereof and another pair ofparallel slots extending across a transverse diameter on the other sidethereof, and pairs of plates seated in said slots, each pair of platesextending in opposite directions from said platform andarranged parallelto the axis of said mount.

16. A mount for an electron discharge device comprising a tubular memberhaving a cylindrical sleeve at one end, a deflector plate unit includinga pair of apertured platforms, a pair of posts for spacing saidplatforms and aligning the apertures therein, a pair of plates on one ofsaid platforms extending toward the other platform and a second pair ofplates projecting above both platforms, and means for mounting said uniton said sleeve.

17. A mount for an electron discharge device comprising a tubular memberhaving a cylindrical sleeve at one end, a deflector plate unit mountedon said sleeve including a pair of apertured platforms, a pair of postsfor spacing said platforms and aligning the apertures therein, a pair ofplates on one of said platforms extending toward the other platform, asecond pair of plates projectlng above both platforms, and a cylindricalmetallic member extending within said sleeve from the lower platform. t

18. An electron discharge device comprising an enclosing vessel having atubular portion and a conical portion terminating in a. dome portion,said dome portion having a fluorescent coating thereon, said tubular andconical portions having an opaque conductive coating thereon, a tubularextension on said tubular portion and projecting from the end thereof,said extension having a stem, an electron gun assembly supported by saidstem, a deflector plate unit suported by said tubular extension andprojecting into said tubular portion, and friction contact fingersmounted on said deflector plate 'unit and engaging the conductivecoating of said tubular portion.

-19. An electron discharge device comprising an enclosing vessel havinga tubular portion and a conical portion terminating in a dome portion,said dome portion having a fluorescent coating thereon, said tubular andconical portions having an opaque conductive coating thereon, a tubularextension on said tubular portion and projecting from the end thereof,said extension having a stem, an electron gun assembly supported by saidstem, an apertured platform supported from said tubular extension withinsaid tubular portion, spacing posts extending from said platform, asecond apertured platform supported on said posts, pairs of deflectorplates extending in opposite directions from said second platform, andconductors attached to said plates being sealed between the junction ofsaid tubular portion and said tubular extension.

20. A cathode ray discharge device comprising an enclosing vessel havinga dome portion, a conical portion, a tubular portion and a tubularextension having an intermediate 'bulbous portion sealed to said tubularportion to form a coaxial inner tubular member within said tubularportion, a coating of carbon on said conical and tubular portions, theextreme end of said tubular extension having a reentrant stem, acircular platform supported on said stem, an indirectly heated cathodemounted on said platform, a cylindrical modulating electrode surroundingsaid cathode and seated on said platform, an elongated tubular focussinganode extending beyond said platform and having apertured baflle discsat opposite ends thereof, a plurality of braces supporting said anodeout of contact with said platform and in alignment with said cathode andelectrode, a copper sleeve sealed to the edge of said inner tubularmember, a metallic platform having a ring extension fitted into saidsleeve and secured thereto, a hollow accelerating anode carried by saidring overlapping one end of said focussing anode, a pair of postsextending above said platform, an insulating platform secured to saidposts and having an aperture in alignment with the aperture in saidmetallic platform, a pair of parallel deflector plates extending fromsaid insulating platform toward said metallic platform, a second pair ofdeflector plates extending fromsaid insulating platform toward said'domeportion and arranged transversely to said first pair of plates, metallicspring members secured tosaid insulating platform and engaging thecoating on said tubular portion, individual conductors for each of saidplates, and an additional conductor secured to one of said posts,

all of said conductors being sealed in the Junetion of said tubularportion and said bulbous portion. I

21. In an electron discharge device, an electron gun assembly comprisinga stem, a platform supported by said stem, a. cathode supported abovesaid platform along the axis thereof, and an elongated tubular anodeprojecting beyond said cathode and having a portion surrounding one endof the cathode.

said platform along the axis thereof, an elongated tubular anode oflarger diameter than said cathode surrounding and projecting beyond saidcathode, and a plurality of equally spaced diagonal braces attached tosaid anode intermediate the ends thereof and connected to said stemlVICTOR L. RONCI.

